This application claims the priority of German patent Application No. 199 44 378.5 filed Sep. 16, 1999, which is incorporated herein by reference.
The invention relates to an apparatus or producing rifling grooves in a weapon barrel. More particularly, the present invention relates to such an apparatus in which a drawing head that rotates about its longitudinal axis is drawn through the respective weapon barrel by a drawing rod, thereby cutting the rifling grooves into the inside surface of the weapon barrel with corresponding drawing knives disposed on the drawing head.
In known apparatuses of this type, the respective drawing head has a plurality of crown-like drawing heads that corresponds to the number of rifling grooves to be produced. Because the weapon barrels have a very hard surface, the rifling grooves cannot be produced in a single drawing process. That is, the drawing head must be drawn through the weapon barrel multiple times, with a new, longer (e.g., increasing by 0.04 mm) set of drawing knives being inserted into the drawing head for each drawing process. This process is continued until the specified groove depth, or example, 1.2 mm, is attained.
A disadvantage of this known apparatus is that the exchange of the drawing knives renders the production of rifling grooves in weapon barrels unusually time-consuming and costly.
It therefore is the object of the invention to provide an apparatus for producing rifling grooves, with which the grooves can be produced at a significantly lower cost than with the known apparatuses.
The above object is achieved according to the invention by an apparatus for producing rifling grooves in a weapon barrel, in which a drawing head that rotates about its longitudinal axis is drawn through the respective weapon barrel by a drawing rod, and the rifling grooves are cut into the inside surface of the weapon barrel with corresponding drawing knives disposed on the circumferential surface of the drawing head, and wherein:
the drawing head includes a central fastening arbor, which is connectable at one end to a drawing rod, an adjusting arbor, which is mounted on and surrounds the circumference of the fastening arbor in at least a partial region, and is displaceable in the direction of the longitudinal axis of the drawing head, and a carrier member, which surrounds the circumference of the adjusting arbor in at least a partial region, and in which holders that receive drawing knives are disposed;
the holders are disposed in the carrier member for displacement radially outwardly, counter to the pressure of a spring, and are supported on their ends facing the adjusting arbor by slanted end surfaces that rest on corresponding conical regions of the adjusting arbor such that the axial displacement of the adjusting arbor effects the radial displacement of the holders, and thus of the drawing knives; and
the holders are distributed on the carrier member in at least two axially spaced regions that are annular when seen in the circumferential direction. Further, particularly advantageous, embodiments of the invention are disclosed.
The invention is based on the concept of providing the drawing head with a central adjusting arbor, with which all of the drawing knives can be displaced outward simultaneously. Thus, in the production of the rifling grooves, the drawing knives no longer need to be exchanged in a time-consuming process. Instead, the setting of the drawing blades is altered with the aid of the adjusting arbor.
For the simultaneous displacement of the drawing knives, the holders that receive the knives are supported on their side facing the adjusting arbor by slanted end surfaces on corresponding conical, annular regions of the adjusting arbor such that the axial displacement of the adjusting arbor effects the radial displacement of the holders, and thus of the drawing knives.
The holders are distributed over at least two regions that appear annular when seen in the circumferential direction.
It has proven advantageous for the drawing knives to be formed by the corresponding ends of turning plates. This permits a worn drawing knife to be replaced with a new one merely through the displacement or rotation of the turning plate. At most, it is only necessary to replace the entire turning plate, but not replace all of the crowns, as in the known apparatuses.
Furthermore, upon a modification of the format of the drawing surface, it is not necessary to exchange all of the crowns. Instead, only the turning plates are exchanged.
The surface of the turning plates is preferably coated. The selection of the surface coating allows the inside surface of the weapon barrel to be adapted easily in the region of the rifling grooves to meet its corresponding requirements. Further details and advantages of the invention ensue from the following embodiment, which is explained in conjunction with the figures.